Directive antenna



Set. W, 1946.

H. G. BUSIGNIES 7,250?

DIRECTIVE ANTENNA Filed Oct. 30, 1941 2 Sheets-Sheet l iHiHilli 15zmwswvraa ELE SOURCE DIRECTIVE ANTENNA Filed Oct. 30, 19 41 2Sheets-Sheet 2 Patented Sept. 10, 1946 ZAQZZSG DIRECTIVE ANTENNA HenriG. Busignies, Forest Hills, N. 1., assignor to Federal Telephone andRadio Corporation, a

corporation of Delaware Application ()ctober 30, 1941, Serial No.417,152

(Cl. 250-1l) 10 Claims.

This invention relates to directive antenna systems, and in particularto improvements in variably directive devices for transmitting and/orreceiving purposes.

It is an object of the invention to provide improved means for varyingthe directivity of an antenna.

More specifically, and with regard to directive antennas, it is anobject to provide improved means for periodically rendering an antennarotatingly directive throughout a generally conical orbit about the axisof said orbit.

Still more specifically, it is an object to provide means forperiodically rotating the directional axis of a directive antenna at aconstant angle with the axis of rotation, whereby the locus of saiddirectional axis is a generally conical orbit about the axis ofrotation.

Another object is to provide an improved reflector of radiant energy.

It is also an object to provide an improved absorbent of radiant energy.

A further object is to provide improved means for varying impedanceoffered to radiant energy radiated or being detected by an antennawhereby directional transmission or reception may be obtained.

A more specific object is to provide means for utilizing a movingionized field in conjunction with an antenna for obtaining directionaltransmission or reception.

A still more specific object is to provide means for setting up anionized field shifting eccentrically about an axis.

Other objects and various further features of novelty and invention willhereinafter be pointed out or will become apparent to those skilled inthe art from a reading of the following specification in conjunctionwith the drawings included herewith. In said drawings,

Fig. 1 is a schematic showing of a device for producing an eccentricallyshifting ionized field in accordance with features of the invention;

Figs. 2 and 3 illustrate schematically how a device according to Fig. 1may be employed in cooperation with an antenna to producenovel directiveeffects in accordance with the invention;

Fig. 4 illustrates schematically an alternative embodiment of the deviceshown in Fig. 1;

Fig. 5 illustrates schematically a, further alternative embodimentillustrative of the invention; and

Figs. 6 and. 7 are plan view showings of certain elements in theapparatus of Fig. 5.

In connection with certain types of radio direction finders, it has beenproposed to transmit radiant energy periodically in a plurality ofdifferent directive senses and to employ received. reflections of suchenergy to determine distance, direction, or other characteristics of areflecting body. Alternately, and for similar purposes, some of thesesystems propose transmitting radiant energy in a constant generallydirectional sense while rendering a receiving antenna periodicailyresponsive to received reflections of such energy as reflected fromvariously located bodies. Such systems have been disclosed, for example,in my copending application entitled Aircraft Indentifier, filed on evendate herewith.

The above mentioned application related particularly to radio apparatusfor detecting the location of aircraft or other reflecting bodies andproposed the use of an antenna system which was recurringly directivethroughout a generally conical orbit. A mechanical set up was disclosedfor producing the desired directivity pattern, and it was also mentionedtherein that either a wholly electrical system or a rotating ionizedfield in accordance with the present invention could be employed.

Broadly speaking, the present invention proposes to use the propertiesof an ionized field either to absorb or to refiect radiant energy inorder to obtain novel directive effects. A chamber filled with anionizable medium and appropriately provided with electrodes for ionizingthe same is suitably disposed with respect to an antenna whereby theionized field present therein ma either reflect or absorb energy beingradiated from or receivd by the antenna. Preferably, the electrodeswithin the chamber are so disposed and energized that a shifting ionizedfield is set up therein, which field shifts eccentrically of an axis ofthe antenna with substantially uniform density throughout its cycle ofshifting operation.

Fig. 1 shows schematically a device for setting up such an eccentricallyshifting, preferably eccentrically rotating, ionized field. The devicecomprises a chamber 5 preferably of generally circular cross section andhaving a plurality of electrodes 6, i, 8. 3, H therein. Chamber 5 may befilled with an ionizable gaseous medium, such as neon, for example, Inthe form shown, chamber 5 is provided with two pairs of diametricallyopposed electrodes, all spaced equally from a generally centralelectrode member iii. In accordance with the embodiment shown in Fig. l,at any instant the ionized field preferably extends over substantially aquadrant sector of the cross section shown, and is thus set up betweenthe electrode I9 and either one or two adjacent of the outer electrodes.

A suitable circuit for energizing the electrode system so as to set upthe desired eccentrically rotating field also shown in Fig. 1. In theform shown, two preferably equal voltages spaced 90 wi in respect toeach other, may be generated by the two phase alternator H and suppliedto potentiometers i2 and 53 respectively. The midpoints ofpotentiometers l2 and it are connected to the central electrode H), asis indicated. by the ground connection. Each end of potentiometer I2 isconnected to electrodes of one pair of op posed electrodes 9 throughrectifier means It, i5 respectively, and each end of potentiometer I3 isconnected to electrodes 5 and 8 of the other pair of opposed electrodesthrough rectifier means it, ll.

With the circuit 50 described. an ionizing potential ma first be set upsay. between electrodes 6 and IE1. It is clear that this potential isset up when the voltage across potentiometer I3 as generated by Winding5 lb of the alternator is a maximum and in the direction indicated bythe arrow E8. No ionizing potential will be set up between electrodes 8and iii at this instant due to the blocking operation of rectifier Hi,as will be clear. As alternator ll continues to rotate, the voltagegenerated in winding Hb will decrease and a voltage will appear acrosspotentiometer ,2 as generated by winding Ila. This voltage may be in thedirection indicated by arrow l9, and due to the passing action ofrectifier I4 and the blocking action of rectifier 45, will begin to setup an ionizing potential between electrodes 1 and iii. The effect ofdecreasing ionizing potential between electrodes ii and ill andincreasing ionizing potential between electrodes 5 and I ll will bebodily to displace the sectoral ionized pattern in a clockwise senseabout electrode l6 and when the voltage across potentiometer l2 reachesa maximum in the direction i9, the ionized sector will appear whollybetween. electrodes l and IE as will be clear. Thus, it is possible togenerate an ionized field rotating eccentrically about an axis, and theuse of such an ionized field will now be described in connection withtwo types of antenna structures.

In Fig. 2, I show how the eccentrically rotating field may be employed.as a radiant energy absorber to produce desired directive effects. InFig. 2, chamber 5 is shown in partly broken away elevation and disposedpreferably concentrically with the axis of a directive antenna structure20 which may be employed in conjunction with ap-- propriate transmitteror receiving means 2|. It is clear that by successively eccentricallyblocking out the portions of the directive pattern generated by antennaEll, novel directional transmitting or receiving eifects may beobtained. In the case described, if antenna 28 is a transmittingantenna, the pattern of radiated energy will be periodically displacedeccentrically of the axis of antenna throughout a generally conicalorbit.

In the form shown in Fig. 3, I show how an eccentrically rotatingionized field may be employed as a reflector to produce noveldirectional effects in accordance withthe invention. Here again, achamber 5, containing the ionizable me-, dium, is shown in partly brokenawa elevation but is preferably shaped generally parabolically forbetter reflecting and focussing purposes. In connection with such areflector, a dipole 22 may be employed as the radiator or receiver ofradiant energy and is preferably disposed along the axis of chamber 5'and generally at the focal point thereof. In the sense of Fig. 3,antenna 22 will have a normal radiation generally to the left and to theright symmetrically about the axis thereof. Energy radiated generally tothe right of antenna 22 will however. strike the eccentrically rotatingionized field produced in chamber '5. It is clear that the efiect ofsuch a field will be to reflect a portion of such energy generally tothe left, thus reinforcing radiation to the left and providing anoverall maximum radiation periodically rotating eccentrically about theaxis of antenna 22.

In an alternate preferred form of the invention, I provide means forextending the sector comprising the ionized field to cover an aregreater than that possible with the apparatus disclosed in connectionwith Fig. 1. Fig. 4 shows a circuit for generating such a field in.which the ionized area extends over substantially three quadrants ofthearea comprehended within the outer electrodes. The chamber 5 andelectrodes 6, l, 8, 9, it ma be the same in structure as in the case ofFig. l. As also in the case of Fig. 1, alternator H may supplysubstantially equal voltages in quadrature relation to potentiometers l2and I3 respectively. The midpoints of these potentiometers and centralelectrode H) are again grounded. However, each of the lines connectingterminals of potentiometers l2 and I 3 to the outer electrodes isprovided with rectifiers 23, 24, 25, 26 and appropriately polarizedbatteries 21, 23, 29, 30. Batteries 2? 39 may supply sufiicientpotential for ionization purposes and rectifiers 23 26 preferably passsuch potential and block an excess thereover.

The effect of such a structure will be at any instant to set up anionized field over a sector comprising substantially the area betweenany three of the outer electrodes and the central electrode inapproximately the following manner. Consider again the instant in whichvoltage generated across potentiometer I3 is a maximum in the directionIt. Rectifier 23 will serve to block an application of potential betweenelectrodes 5 and I3 and an ionized field may thus, in the absence ofbatteries 21, 28, 29, 39, be set up between electrodes 8 and i0.However, simultaneously, batteries 22', 28, 29, 3B are all supplyingsufficient potential for ionization and such potential is opposed insense to that set up between electrodes 6 and lil due to the voltage is.As a result the net potential applied between electrodes 6 and It at theinstant under consideration is in the neighborhood of zero (or at leastshould preferably be less than an ionizing potential) so that at anyinstant a quadrant or other small sector may be non-ionized.

It will now be clear, recalling the discussion of operation of thecircuit of Fig. 1 that, as the maximum voltage supplied by alternator Hrotates in phase, the non-ionized quadrant or other small sector justreferred to may rotate accordingly. It is thus possible to set up aneccentrically rotating ionized field which at any instant maycomprisesubstantially more than half the area within the outer electrodes.

In the embodiments of the invention thus far described it may be thatthe central electrode member 10 will have undesirable reflecting,distorting or'other effects upon radiated or received energy. In thatevent I propose an alternative embodiment illustrated in one form inFig. 5. This alternative apparatus eliminates any need for a centralelectrode and provides the possibility of extending the ionized fieldsector to include a wide range of arcs from, say a quadrant up to threequadrants.

A in the case of the previously discussed structures, the embodimentaccording to Fig. 5 comprises within an envelope 40 an ionizable mediumand a plurality of electrode structures AA', B-B' H-H. These electrodestructures are preferably equally spaced generally along thecircumference of an imaginary circle. In accordance with features of theinvention and for purposes which will later become apparent, each suchelectrode structure comprises a plurality of closely-spaced electrodes,possible preferred forms of which have been illustrated in Fig. 6 and 7.The form shown in Fig. 6 depicts electrode structure A--A a comprisingtwo electrodes A and A, each having protruding or lobeshaped portions4!, ll and correspondingly recessed lobe-shaped portions 42, 32'. In theform shown in Fig. '7 electrodes A and A each comprise a plurality ofrelatively well spaced electrode surfaces 33. it, and each of thesurfaces say 43 of electrode A is disposed between surfaces 63' ofelectrode A. Preferably electrodes A and A are provided with a largeplurality of lobes and recesses in the Fig. 6 form and with a largeplurality of surfaces in the Fig. 7 form, whereby the alternate use ofeither electrode A or A will have little efiect in displacing an ionizedfield set up between electrode structure AA' and any other electrodestructure, as will later be clear.

In Fig. 5 the various electrode structures AA', BB, etc. are shown witha solid-line designation, e. g. A, and a dotted line, e. g. A. Such amethod of designation indicates schematically that the respectivesurfaces of both electrodes A and A are coplanar (perpendicular to thesense of Fig. 5) and insulatingly spaced with respect to each other, asclearly shown in Figs. 6 and 7.

In the embodiment of Fig. 5, I preferably employ means supplying aplurality of phase-displaced voltages for energizing appropriate pairsof electrodes within chamber 5'] to set up a desired rotating ionizedfield. In the preferred form shown this plurality of voltagescorresponds with the number of electrode structures AA', B-B, etc. andmay be supplied by an appropriately Wound alternator 44. Alternator 44includes a number of output terminals a-a, 72-42 71-h, yielding acorresponding number of alternating voltages phase displaced preferablyequally with respect to each other. The mode of connecting the variousphase outputs of alternator M to electrode structures AA', BB, etc.shown in Fig. 5 is merely illustrative, and it is to be understood thatother connection schemes may be devised to accomplish substantially thesame results.

In the form shown, successive output windings of alternator a l areconnected between an electrode of one electrode structure and that ofanother structure displaced a few structures away. Specifically, theoutput of winding aa' is applied between electrodes A and D, the outputof winding bb between electrodes B and E, and soon.

Let us now consider the effect of successive maximum voltages in thealternator windings during operation. For illustration, assume theinstant at which voltage in winding a-a' is a maximum in one direction.Voltages in windings bb' and h'-h will be somewhat less, but in the samesense; and voltages in windings c-c' and CIA 6 g'g may be rather low,but also in the same sense.

The effect of a, maximum and large voltage applied between electrodes Aand D will be suflicient to produce an ionized field therebetween tocover a substantial chord of the tube All. The effect of less voltagebeing applied simultaneously between electrodes B and E, and C and H,respectively, may be to set up an ionized field therebetween, if thevoltage thus provided be sufficient to produce ionization. As regardsthe relatively low voltages from windings 0-0 and gg, respectively, itis not likely that they will be sufficient to produce ionization betweenelectrodes C and F, and B and G, respectively. The net effect ofapplication of potentials at the instant under consideration will thusbe to set up a localized ionization field extending over the sectorgenerally defined by a starting limit at electrode structure H-H andclockwise around to electrode structure E-E, as will be clear.

Now, by considering successive instants, that is, as the output ofWinding aa decreases in magnitude and as, say the output of winding b--bincreases to a maximum, it will clearly be seen that the ionized fielddefined by the aboveidentified sector will be bodily displacedcorrespondingly about the axis of tube 4a.

In order to simplify showing and explanation of the circuit of Fig. 5 Ihave necessarily omitted a showing of additional circuit elements whichit may be desirable to add. For example, some kind of output controlmeans may be associated with alternator G l, whereby the maximum outputsof all the windings a-a, bb', etc. may be simultaneously regulated. Theutility of such a regulatory system will be very apparent, for windingoutput may at one extreme be so adjusted as to yield ionizing potentialsonly when winding output is at a maximum. On the other hand, windingoutput may be so increased that ionizing potentials are produced inseveral adjacent windings at once.

The effect of such regulation will be seen to vary the angular size ofionized field produced. In the former of the above extreme conditions ofoutput assumed, and at the instant when winding a-a' is yielding amaximum voltage, no other windings supply adequate voltage forionization, so that the chord between electrode structures AA and D-D'will be the only ionized field. In the latter condition, even the outputvoltage of windings cc and gg may be suffic ently large to produce aslight degree of ionization. As a result then, at the assumed instant,the ionized field may extend almost completely around the device. It isto be noted that, inasmuch as the degree of ionization varies somewhatwith potential applied, the ionized field may extend completely aroundtube fill, and at the same time be locally ionized to an extreme extent,due to the various ionizing potentials applied between electrodes ofvarious electrode structures. Thus, in the latter condition assumed,ionization may be taking place between at least one electrode of all theelectrode structures, but there will be a localized extremely highlyionized field extending roughly over the sector HI-I clockwise to E--E.

While I have described my invention particularly in conjunction withdevices employing a plurality of electrodes and means for appropriatelyenergizing these electrodes to obtain an eccentrically rotating orotherwise shifting ionized field, it is clear that other methods may be7 employed. For example, it is known that an alternating voltage of highenough frequency may be sufficient to produce a steady ionized field.

It will be observed that the circumferentially disposed electrodes inall showings oi the discharge device are neither shovm as having fiatnor generally arcuate surfaces, but rather as having a slightlyundulatory form. This showing has been made to call attention to thefact that some sort of design and experimental work will be necessarywith respect to these surfaces in order to obtain the most uniformstrength of ionized field between electrodes as that field rotates orshifts eccentrically in accordance with the invention. 1, therefore,consider that the precise form of electrode finally to be adopted ispurely a matter of design.

While the foregoing description has been made in 133.1 ticular detail inconnection with the preiercd forms illustrated, it is to be understood.at many modifications thereof may be made he scope and spirit of thisinvention. at I claim is:

A directive antenna system comprising a said element, said reflectorcomprising an envelope of non-conductive material, ionizable meanswithin said envelope, electrode means for ionizitrg said ionizablemeans, said electrode means including electrodes disposed generallyalong the circumference of a circle, and means [or successivelyenergizing said electrodes, whereby ionization within said envelope iseccentrically localized and rotated about the axis of said eccentricity.

2. A directive antenna system according to cla m 1, wherein saidradiating element is generally uni-directionally directive and saidreflector is disposed transverse to substantially all the radiation ofsaid element.

3. A radiant energy directional. system including antenna means, meansdisposed in proximity to and positioned to reflect energy directed bysaid antenna means for setting up a locally ionized field, and means forperiodically displacing said ionized field to variably effect thedirectional effect said energy.

4.. A directionally responsive receiving antenna system including areceiving element, a rehector disposed adjacent said element to reflectenergy thereto, said reflector comprising an en velope non-conductivematerial, ionizable means wi *1 said envelope, electrode means forionizing said ionizable means, said electrode means including electrodesdisposed generally along the circumference of a circle, and means forsuccessively energizing said electrodes, Whereby ionization within saidenvelope is eccentrically localized and rotated about the axis of saideccentricity.

5. A directive antenna system according to claim 1, wherein saidreflector is disposed generally transverse to radiation from saidelement.

6. A directive antenna system according to claim 1, wherein saidreflector is disposed generally transverse to radiation from saidelement and said chamber is of generally parabolic cross section.

7. A directionally responsive antenna system comprising an antenna fortranslating electromagnetic waves, a reflector for said waves disposedadjacent said antenna, said. reflector comprising an envelope ofnon-conductive material, ionizable means within said envelope, aplurality of opposed pairs of electrodes within said envelope forionizing said ionizable means to produce an ionized path, and means forsuccessively energizing electrodes in a predetermined sequence wherebythe configuration of said path is varied to change the directivity ofsaid antenna system.

8. A reflector for a directive antenna system comprising an envelope ofnon-conducting material, the shape oi said envelope being substantiallyparaboloidal, ionizing means Within said envelope for producing anionized path, said ionizing means comprising an ionizable gaseous mediumand a plurality of pairs of electrodes, said electrodes being disposedalong a generally circular circumference near the periphery of saidtube, means providing a plurality of phase-displaced voltages equal innumber of said pairs of electrodes, and means for sequentially applyingsaid voltages to said pairs of electrodes, whereby the configuration orsaid path is varied to change the directivity of said antenna system.

9. A reflector for a directive antenna system in accordance with claim8, wherein each electrode of said opposed pairs comprises a plurality ofclosely spaced electrode members, each of said members havinglobe-shaped portions in spaced relation to a corresponding lobe-shapedportion of another of said members.

10. A reflector for a directive antenna system in accordance with claim8, wherein each electrode of said opposed pairs comprises two closelyspaced members, each of which comprises relatively widely spacedelectrode surfaces, and each of the surfaces of one of said members isdisposed between the surfaces of another of said members.

HENRI G. BUSIGNIES.

